Goldberg is a polemicist, not a historian, and frankly not all that competent even in his acknowledged line. Do better - by not ignoring the Night of the Long Knives, for a start.
That's an appeal to authority and with that not relevant. What about the night of the long knives means the NDSAP was not ideologically aligned with socialism. Parties which make socialism part of their platform run the gamut from social democrat parties in western Europe to the Khmer Rouge and anything in-between. There's plenty of blood on 'socialist' hands. That does not mean there is blood on all socialist hands. The same goes for nationalism.